If Twin Metals' controversial copper-nickel mine near the Boundary Waters Canoe Area Wilderness is approved, then it will be built with union labor.

The company and the Iron Range Building and Construction Trades Council are set to formally sign a project labor agreement at a ceremony in Ely Wednesday. According to union president Mike Syversrud, the agreement ensures local, unionized workers will be hired to build the large underground copper-nickel mine, dry-stack tailings storage and other facilities.

All of that could take an estimated 2 to 2.5 million construction hours, Syversrud said. In a news release, Twin Metals said the project "will be similar in scope to the construction of U.S. Bank Stadium in Minneapolis."

"It is huge," Syversrud said of the agreement. "For starters, it's going to be three years of work for our members."

Twin Metals, owned by Chilean mining conglomerate Antofagasta, is hoping to build its mine near Ely, within the Rainy River Watershed and on the edge of the BWCAW. Opponents of the project argue toxic runoff from the mine and tailings would pollute the BWCAW.

But any construction at Twin Metals is likely years away and hinges on whether state and federal regulators approve the project. Twin Metals has not formally applied for permits, but the company has said it plans to submit its mine plan of operations later this year, which would trigger the yearslong permit process.

PolyMet, the first copper-nickel mine to become fully permitted in Minnesota, started the regulatory process in 2004 and earned its permits 14 years later.

Similarly, PolyMet signed a project labor agreement promising union labor in 2007, long before its had permits. PolyMet still needs to raise almost $1 billion in financing before it can begin construction.

Twin Metals CEO Kelly Osborne said in statement to the News Tribune Tuesday that the company is "proud" to work with unions and noted it used union labor when it built its core storage facility in 2013.

“As we prepare to file our mine plan of operations, it’s important that we further solidify our partnership with labor and ensure that the construction phase of our project will be completed by professionals whose specialized skills are essential to the premier quality work we insist on," Osborne said.